Preemptive measures for exceptions and correct for repository snapshots

[AlexandraRoatis]

Description

1. Added catch statements and default return values for non-critical functionality relating to the PendingBlockStore.
2. Copying the reference to the pendingBlockStore when creating snapshots to avoid null pointer exceptions if the store is accessed from the snapshot.

Type of change

Insert x into the following checkboxes to confirm (eg. [x]):

• Bug fix.
• New feature.
• Enhancement.
• Unit test.
• Breaking change (a fix or feature that causes existing functionality to not work as expected).
• Requires documentation update.

Testing

Please describe the tests you used to validate this pull request. Provide any relevant details for test configurations as well as any instructions to reproduce these results.

• existing test suite

Verification

Insert x into the following checkboxes to confirm (eg. [x]):

• I have self-reviewed my own code and conformed to the style guidelines of this project.
• New and existing tests pass locally with my changes.
• I have added tests for my fix or feature.
• I have made appropriate changes to the corresponding documentation.
• My code generates no new warnings.
• Any dependent changes have been made.

[AionJayT]

LGTM, thanks for the fix

[arajasek]

🚢